Border Structures for Displays

ABSTRACT

An organic light-emitting diode display may have an active area that contains pixels and an inactive area. The inactive area of the display may be provided with opaque masking layer structures having an appearance that matches the active area of the display when the pixels are off and are not displaying images. The opaque masking layer structures may include a polymer layer coated with a layer of metal. The display may have pixels with anodes and a cathode layer. The anodes may be formed from metal pads. Dummy structures such as a dummy cathode and dummy anodes may be formed in the inactive area. A circular polarizer in the display may overlap the active area and the inactive area or may overlap the active area without overlapping some or all of the inactive area.

This application is a continuation of U.S. patent application Ser. No.14/751,000, filed on Jun. 25, 2015, which is hereby incorporated byreference herein in its entirety. This application claims the benefit ofand claims priority to U.S. patent application Ser. No. 14/751,000,filed on Jun. 25, 2015.

BACKGROUND

This relates generally to electronic devices, and, more particularly, todisplays for electronic devices.

Electronic devices such as cellular telephones, computers, and otherelectronic devices often contain displays. Organic light-emitting diodedisplays are thin displays that can be used to display color images fora user. The pixels in an organic light-emitting diode display eachinclude a light-emitting diode having an anode and cathode. A circularpolarizer layer may overlap that pixels to help suppress ambient lightreflections from diodes.

Organic light-emitting diode displays have inactive border regions thatcontain display driver circuitry but do not contain any pixels. To blockdisplay driver circuitry in the inactive border regions and internalcomponents in an electronic device from view, a display may be providedwith a bezel that overlaps the border of the display. In some devices,the front surface of the display is covered with a protective coverglass layer.

The use of a bezel can be avoided by forming an opaque masking layersuch as a layer of black ink on the underside of the cover glass layeralong the edge of the display. When the display is off, the display willhave a dark color. Although the black ink border also has a dark color,there can be a noticeable mismatch between the appearance of the blackink border and the dark color of the display. This mismatch may beaesthetically undesirable and distracting to the user.

It would therefore be desirable to be able to provide improved borderstructures for electronic device displays.

SUMMARY

A display such as an organic light-emitting diode display may have anactive area that contains pixels that display images for a user. Thedisplay may also have an inactive area that does not contain any pixelsand that does not display images for the user. The display may bemounted in a housing of an electronic device. A transparent displaycover layer may be used as an outer layer of the display.

The inactive area of the display may be provided with opaque maskinglayer structures having an appearance that matches the active area ofthe display when the pixels are off and are not displaying images. Thedisplay may have an organic light-emitting diode display layercontaining an array of the pixels. Opaque masking structures may beformed as part of the organic light-emitting diode display layer or maybe formed as the structures that are attached to the display cover layeralong the edge of the organic light-emitting diode display layer.

The opaque masking layer structures may include a polymer layer coatedwith a layer of metal. The organic light-emitting diode display may havepixels with anodes and a cathode layer. The anodes may be formed frommetal pads. The anodes may be separated from the cathode layer by apolymer layer. A circular polarizer in the display may overlap displaycover layer. The circular polarizer may overlap the active area and theinactive area or may overlap the active area without overlapping some orall of the inactive area. Dummy structures may be formed in the inactivearea to ensure that the inactive area has an appearance matching that ofthe active area. The dummy structures may include a dummy cathode anddummy anodes that are formed respectively from portions of the cathodelayer and the metal layer that forms the anodes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an illustrative electronic device inaccordance with an embodiment.

FIG. 2 is a top view of an illustrative electronic device display inaccordance with an embodiment.

FIG. 3 is a cross-sectional side view of an illustrative organiclight-emitting diode pixel in accordance with an embodiment.

FIG. 4 is a cross-sectional side view of an illustrative electronicdevice in accordance with an embodiment.

FIGS. 5, 6, and 7 are cross-sectional side views of illustrative opaqueborder structures in accordance with embodiments.

FIG. 8 is a cross-sectional side view of an illustrative electronicdevice having a display with a border in accordance with an embodiment.

FIGS. 9 and 10 are cross-sectional side views of displays having bordersin accordance with an embodiment.

FIG. 11 is a cross-sectional side view of an illustrative display with aborder in accordance with an embodiment.

FIG. 12 is a cross-sectional side view of a display having an opaqueborder layer that overlaps an edge of an organic light-emitting diodedisplay layer in accordance with an embodiment.

FIG. 13 is a cross-sectional side view of an illustrative device with ahousing structure that helps retain a display in accordance with anembodiment.

DETAILED DESCRIPTION

An electronic device such as electronic device 10 of FIG. 1 may containa display such as display 14. The display may have pixels organized inan array. The pixels may form an active area AA of the display thatdisplays images for a user. Active area AA may have a rectangular shapeor other shapes (e.g., area AA may be circular, rectangular with roundedcorners, elliptical, etc.). An inactive border area IA in which nopixels are present may run along one or more of the edges of the activearea. For example, in a configuration in which active area AA has arectangular shape, inactive area IA may have a rectangular ring shapethat surrounds active area AA. Inactive border area IA may containcircuits, signal lines, and other structures that do not emit light forforming images.

Electronic device 10 may be a computing device such as a laptopcomputer, a computer monitor containing an embedded computer, a tabletcomputer, a cellular telephone, a media player, or other handheld orportable electronic device, a smaller device such as a wrist-watchdevice, a pendant device, a headphone or earpiece device, a deviceembedded in eyeglasses or other equipment worn on a user's head, orother wearable or miniature device, a television, a computer displaythat does not contain an embedded computer, a gaming device, anavigation device, an embedded system such as a system in whichelectronic equipment with a display is mounted in a kiosk or automobile,equipment that implements the functionality of two or more of thesedevices, or other electronic equipment. In the illustrativeconfiguration of FIG. 1, device 10 is a portable device such as acellular telephone, media player, tablet computer, or other portablecomputing device. Other configurations may be used for device 10 ifdesired. The example of FIG. 1 is merely illustrative.

In the example of FIG. 1, display 14 of device 10 is mounted in housing12. Housing 12, which may sometimes be referred to as an enclosure orcase, may be formed of plastic, glass, ceramics, fiber composites, metal(e.g., stainless steel, aluminum, etc.), other suitable materials, or acombination of any two or more of these materials. Housing 12 may beformed using a unibody configuration in which some or all of housing 12is machined or molded as a single structure or may be formed usingmultiple structures (e.g., an internal frame structure, one or morestructures that form exterior housing surfaces, etc.).

Display 14 may be a touch screen display that incorporates a layer ofconductive capacitive touch sensor electrodes or other touch sensorcomponents (e.g., resistive touch sensor components, acoustic touchsensor components, force-based touch sensor components, light-basedtouch sensor components, etc.) or may be a display that is nottouch-sensitive. Capacitive touch screen electrodes may be formed froman array of indium tin oxide pads or other transparent conductivestructures.

Display 14 may be protected using a display cover layer such as a layerof transparent glass or clear plastic. Openings may be formed in thedisplay cover layer. For example, an opening may be formed in thedisplay cover layer to accommodate a button such as button 16. Anopening may also be formed in the display cover layer to accommodateports such as speaker port 18. Openings may be formed in housing 12 toform communications ports (e.g., an audio jack port, a digital dataport, etc.), to form openings for buttons, etc.

Display 14 may include an array of display pixels formed from liquidcrystal display (LCD) components, an array of electrophoretic pixels, anarray of plasma pixels, an array of organic light-emitting diode pixelsor other light-emitting diodes, an array of electrowetting pixels, orpixels based on other display technologies. Illustrative configurationsfor display 14 that are based on organic light-emitting diode displaysare sometimes described herein as an example.

As shown in FIG. 2, display 14 may have rows and columns of pixels 22that form active area AA. Active area AA is used to display images for auser of device 10. Pixels 22 may be formed using one or more layers ofmaterial such as substrate layer 36. Layers such a layer 36 may beformed from flexible polymers or other flexible materials (as examples).Substrate 36 may have left and right vertical edges and upper and lowerhorizontal edges. If desired, substrates such as substrate 36 may havenon-rectangular shapes (e.g., shapes with curved edges, rectangularshapes and other shapes with protrusions that form flexible tails,etc.).

Each pixel 22 may have a light-emitting diode (e.g., an organiclight-emitting diode). The light-emitting diode may have an anode (e.g.,a metal pad), a cathode (e.g., a blanket transparent film formed from atransparent conductive material such as indium tin oxide and/or layersof metal that are sufficiently thin to be transparent), and organicemissive material interposed between the anode and cathode. Each ofpixels 22 may also include thin-film circuitry (e.g., one or morethin-film transistors formed from polysilicon, indium gallium zinc oxideor other semiconducting oxides, or other semiconductors, thin-filmcapacitors, signal routing lines, etc.). The thin-film transistorcircuitry and other circuits of display 14 may be used to apply controlsignals to the light-emitting diodes of pixels 22, thereby creatingdesired images on display 14.

Pixels 22 may receive data signals over signal paths such as data linesD and may receive one or more control signals over control signal pathssuch as horizontal control lines G (sometimes referred to as gate lines,scan lines, emission control lines, etc.). There may be any suitablenumber of rows and columns of pixels 22 in display 14 (e.g., tens ormore, hundreds or more, or thousands or more). In organic light-emittingdiode displays, pixels 22 contain pixel circuits that control theapplication of current to the light-emitting diodes of pixels 22. Thepixel circuits in pixels 22 may contain thin-film transistors havinggates that are controlled by signals on horizontal control lines such aslines G.

Display driver circuitry 20 may be used to control the operation ofpixels 22. Display driver circuitry 20 may be formed from integratedcircuits, thin-film transistor circuits, or other suitable circuitry.Thin-film transistor circuitry may be formed from polysilicon thin-filmtransistors, semiconducting-oxide thin-film transistors such as indiumgallium zinc oxide transistors, or thin-film transistors formed fromother semiconductors. Pixels 22 may have color filter elements ofdifferent colors (e.g., red, green, and blue) to provide display 14 withthe ability to display color images.

Display driver circuitry 20 may include display driver circuits such asdisplay driver circuit 20A and gate driver circuitry 20B. Display drivercircuit 20A may be formed from one or more integrated circuits and/orthin-film transistor circuitry. Gate driver circuitry 20B may be formedfrom integrated circuits or may be thin-film circuitry. Display drivercircuit 20A of FIG. 2 may contain communications circuitry forcommunicating with system control circuitry over path 32. Path 32 may beformed from traces on a flexible printed circuit such as flexibleprinted circuit 40 or other conductive lines. During operation, controlcircuitry in device 10 may supply circuit 20A with information on imagesto be displayed on display 14.

To display the images on display pixels 22, display driver circuitry 20Amay supply image data to data lines D while issuing clock signals andother control signals to supporting display driver circuitry such asgate driver circuitry 20B over path 38. Circuitry 20A may supply signalsto gate driver circuitry 20B on one or both edges of display 14 (see,e.g., path 38′ and gate driver circuitry 20B′ on the right-hand side ofdisplay 14 in the example of FIG. 2).

Gate driver circuitry 20B (sometimes referred to as horizontal controlline control circuitry) may control horizontal control lines (gatelines) G. Gate lines G in display 14 may carry signals for controllingrows of pixels 22 (e.g., signals such as scan signals, emission controlsignals, etc.). The control signals in each row can be used to turn ontransistors in pixels 22 in that row when loading data from the datalines into pixel storage capacitors in those pixels from data lines D).During operation, frames of image data may be displayed by asserting asignals on the rows of display 14 in sequence.

The portion of substrate 36 that contains the array of pixels 22 (i.e.,active area AA) is used in displaying images for a user of device 10.The portion of substrate 36 that contains routing lines and supportingcircuitry such as display driver circuitry 20 (i.e., the portion ofsubstrate 36 in inactive area IA) does not contain any pixels 22 andtherefore does not display images for device 10.

A cross-sectional side view of a pixel 22 in active area AA in anillustrative organic light-emitting diode display is shown in FIG. 3. Asshown in FIG. 3, display 14 may include a substrate layer such assubstrate layer 30. Substrate 30 may be a planar layer or a non-planarlayer and may be formed from plastic, glass, ceramic, sapphire, or othersuitable materials. Configurations for display 14 in which substrate 30is formed from a material such as plastic are sometimes described hereinas an example.

Thin-film transistor circuitry 44 may be formed on substrate 30. Thinfilm transistor circuitry 44 may include anode structures such as anode56 on thin-film layers 52. Layers 52 may include semiconductor layers,metal layers, and dielectric layers that form circuitry 44. Circuitry 44may include transistors and capacitors that form pixel circuits forcontrolling light-emitting diodes such as light emitting diode 64 ofFIG. 3. During operation, light-emitting diode 64 may emit light 24 forpixel 22.

Light-emitting diode 64 may be formed within an opening in pixeldefinition layer 60. Pixel definition layer 60 may be formed from apatterned photoimageable polymer. In each light-emitting diode, organicemissive material 62 is interposed between a respective anode 56 andcathode 42. Anodes 56 may be patterned from a layer of metal oncircuitry 44. Cathode 42 may be formed from a common conductive layerthat is deposited on top of pixel definition layer 40. Cathode 42 may beformed from a transparent conductive material such as indium tin oxide,one or more metal layers that are sufficiently thin to be transparent,or other conductive material that is transparent so that light 24 mayexit light emitting diode 64. In some configurations, anode 56 may beformed above cathode 42 (i.e., the conductive layers for the terminalsof the diodes 64 may be reversed). The configuration of FIG. 3 in whichcathode layer 42 is located above anodes 56 is merely illustrative.

Display 14 may have a protective outer display layer such as displaycover layer 50. The outer display layer maybe formed from a materialsuch as sapphire, glass, plastic, clear ceramic, or other transparentmaterial. Configurations in which the outermost layer of display 14 isformed from a clear layer of glass are sometimes described herein as anexample. This is merely illustrative. In general, the outermost layer ofdisplay 14 may be formed from any suitable material and may be formedwith a thickness sufficient to provide display 14 with damage fromscratches, etc. For example, display cover layer 50 may have a thicknessof 0.05 to 2 mm, 0.1 to 0.5 mm, etc.

If desired, display 14 may include functional layers 48. Functionallayers 48 may include a touch sensor layer, a circular polarizer layer,and other layers. A circular polarizer layer may help reduce lightreflections from metal in thin-film transistor circuitry 44 such ascathode 42 and anodes 56.

Layer 46 may include one or more moisture barrier layers, polymerlayers, adhesive layers, buffer layers, and other structures. Layer 46may help planarize circuitry 44 and may sometimes be referred to as aplanarization layer.

Layers of optically clear adhesive may be used to attach cover glasslayer 50 and functional layers 48 to underlying display layers such asplanarization layer 46, thin-film transistor circuitry 44, and substrate30.

During operation of display 14, current is applied to light-emittingdiodes 64 of pixels 22 in active area AA and active area AA displaysimages for a user of device 10. When display 14 is off, no current isapplied to diodes 64, so no light 24 is emitted by pixels 22. Device 10may be actively used by a user, even when display 14 is off. Forexample, a user of device 10 may listen to music with device 10, eventhough display 14 has been turned off to conserve power. When display 14is off, ambient light in the vicinity of the user can strike the surfaceof display 14. As shown in FIG. 3, for example, ambient light 70 mayilluminate display 44 and may reflect from display 14 at an angle A withrespect to surface normal n to create reflected light 72.

Some conventional displays have display cover glass layers on which aring of black ink is deposited to form an opaque border mask. The blackink mask in this type of arrangement does not have the same appearanceas the display structures in the active area of the display, leading toa mismatch between the appearance of the border and the appearance ofthe active area. Black ink tends to be darker than the active area ofthe display and has an appearance that is relatively insensitive to theangle at which the black ink is being illuminated and viewed (see, e.g.,angle A of FIG. 3). In contrast, the structures of the active area(e.g., the circular polarizer, planarization layer, cathode, anode,etc.) can lead to reflections and thin-film interference effects thatvary from those of a black ink layer. As an example, the metal or othermaterial forming cathode 42 (and anodes 62) may reflect non-negligibleamounts of ambient light 70 from display 14 and thin-film interferenceeffects may cause the color and intensity of the reflected light to varysignificantly as a function of angle A. As a result, the black ink ofconventional borders tends to be noticeably different in appearance thanthe active portion of the display that the conventional borderssurround.

To reduce the difference in appearance between active area AA and borderIA of device 10, device 10 can be provided with border structures thatmatch the appearance of active area AA. The structures may be formedfrom extended portions of an organic light-emitting diode display (e.g.,edge portions of structures formed on substrate 36 of FIG. 2), and/ormay be formed from separate layers of material (e.g., structures formedon the underside of a display cover layer or on a substrate such as apolymer substrate that is attached to the underside of a display coverlayer with adhesive).

Consider, as an example, the illustrative configuration of FIG. 4. FIG.4 is a cross-sectional side view of device 10 in an illustrativeconfiguration in which display 14 has been provided with separate opaquemasking layer structures in inactive area IA that have an appearancethat matches the appearance of active area AA. The cross-sectional viewof FIG. 4 may, as an example, correspond to a cross-section of device 10of FIG. 1 taken across the length of device 10. As shown in FIG. 4,device 10 may have a housing such as housing 12 in which components 80are mounted. Components 80 may include integrated circuits, connectors,sensors, input-output devices, and other circuitry. Components 80 may bemounted on one or more substrates such as illustrative substrate 82.Substrate 82 may be a printed circuit (e.g., a rigid printed circuitboard formed from fiberglass-filled epoxy or other rigid printed circuitboard substrate material or a flexible printed circuit formed from aflexible layer of polyimide or a sheet of other polymer material).

Display 14 may have an organic light-emitting diode display layer suchas display layer (display) 88. Display 88 may be, for example a flexibleorganic light-emitting diode display layer formed from a polyimidesubstrate layer or other suitable substrate (e.g., substrate 30 of FIG.3) and may have pixels 22 such as pixel 22 of FIG. 3.

Display layer 88 may have an active area portion with pixels 22 (i.e.,portion 88A in active area AA) and may have an inactive region thatcontains display driver circuitry 20 but that does not contain pixels 22(i.e., portion 881 in inactive area portion IA1 of inactive area IA).The appearance of inactive portion 881 may match the appearance ofactive area portion 88A. Device 10 may also have opaque masking layerstructures 90 with an appearance that matches portions 88A and 881 ofdisplay layer 88. Opaque masking layer structures 90 may be formed fromone or more layers of material on a plastic substrate or other suitablesupport layer. Display 14 may be mounted to housing 12 using adhesive 92or other suitable mounting arrangements.

Polarizer layer 48′ in layers 48 may be attached to the underside ofdisplay cover layer 50 using adhesive layer 84 (e.g., optically clearadhesive). Display layer 88 and opaque masking layer structures 90 maybe attached to the underside of polarizer layer 48′ using adhesive layer86 (e.g., an optically clear adhesive). If desired, other layers ofmaterial may be interposed within functional layers 48. The example ofFIG. 4 is merely illustrative.

Polarizer layer 48′ may be a circular polarizer to suppress lightreflections from reflective structures (e.g., metal structures such ascathode and anode structures) in organic light-emitting diode layer 88.In the illustrative configuration of FIG. 4, polarizer layer 48′ has amain rectangular portion in inactive area AA and has an extended edgethat covers inactive area portion IA1 of inactive area IA and inactivearea portion IA2 of active area IA. In portion IA1 of interactive areaIA, polarizer layer 48′ may suppress reflections from thin-filmtransistor structures in display driver circuitry 20 (e.g., metaltraces). Polarizer layer 48′ also helps ensure that the appearance ofinactive area IA will be the same as that of active area AA. Forexample, the portion of polarizer layer 48′ in portion IA2 of inactivearea IA can help ensure that reflections and thin-film interferenceeffects in inactive area IA match those of active area AA.

FIGS. 5, 6, and 7 are cross-sectional side views of illustrativeembodiments of opaque masking layer structures 90. In the example ofFIG. 5, structures 90 have a substrate layer such as layer 94 and one ormore layers of material that are supported by layer 94 such as layer 96.Substrate layer 94 may be a polymer film or other suitable material(e.g., a dielectric layer, etc.). Layer 96 may be a metal coating havinga reflectively that helps structure 90 exhibit the same appearance asactive area AA of display layer 88. Layer 96 may be formed from a metalor other reflective material and may be formed from the same materialthat forms cathode 42 or a different material. Layer 96 may be a planarlayer (e.g., a planar metal coating layer on polymer layer 94). Inscenarios in which layer 90 includes metal such as metal coating layer96, it may be desirable to ground metal layer 96 to a ground terminal(see, e.g., ground 100 of FIG. 5). Structures 90 may be formed withgrounding paths such a grounding path 98 (e.g., a via) or othergrounding paths may be used to ground metal layer 96 (e.g., paths formedfrom silver paint or other conductive paint, paths formed fromconductive adhesive, paths formed from conductive gaskets, paths formedfrom conductive traces through display 88, and/or other suitable groundpaths). The use of a via structure for forming path 98 is merelyillustrative.

In the example of FIG. 6, structures 102 have been formed on substrate94 and covered with layer 104. Layer 96 has been formed on layer 104.Layer 94 may be a substrate layer formed from a polymer or othermaterial (e.g., a dielectric layer). The patterned structures of layer102 may be metal structures (e.g., metal pads of the same size andthickness of anodes 56 of FIG. 3 or having different sizes and/orthicknesses). Layer 104 may be a polymer layer or a layer of othermaterial (e.g., a layer of material with an index of refraction and/orother optical properties similar to that of layer 46 of FIG. 3 or othersuitable layer of material). Layer 96 may be a metal layer or a layer ofother material. Layers 94, 102, 104, and 96 may be configured so thatthe reflectivity and thin-film optical interference effects ofstructures 90 match those of layer 88 in active area AA. Optional viasor other structures may be used to form a grounding path such as path 98to short layer 96 to ground terminal 100.

In the illustrative configuration of FIG. 7, structures 90 have asubstrate layer such as layer 94 (e.g., a polymer layer or other layersuch as a dielectric layer). Structures 102 such as metal pads may beformed on substrate 94. Material 110 may be formed on structures 102.Material 110 may be emissive material such as material 62 of FIG. 3 ormay be material that has an index of refraction and/or other opticalproperties that match material 62. The material of layer 108 may haveoptical properties that match material 60 of FIG. 3. Layer 96 may be ametal layer or other layer of material that has optical properties thatmatch those of layer 42 of FIG. 3. Layer 106 may serve as aplanarization layer and may have optical properties that match those ofplanarization layer 46 of FIG. 3. Layers 94, 102, 110, 108, 96, and 106are preferably configured so that the reflectivity and thin-film opticalinterference effects of structures 90 match those of layer 88 in activearea AA. If desired, vias or other structures may be used to form agrounding path such as path 98 to short layer 96 to ground 100.

FIG. 8 is a cross-sectional side view of device 10 showing anotherillustrative arrangement that may be used to ensure that inactive areaIA has an appearance that matches that of active area AA. Thecross-section of FIG. 8 is of the type that may be taken across thewidth of device 10 of FIG. 1 (as an example).

As shown in FIG. 8, display 14 may be mounted in housing using adhesive92 (as an example). Display 14 may have a display cover layer such asdisplay cover layer 50. Functional layers 48 may be interposed betweenorganic light-emitting diode display layer 88 and display cover layer50. Components 80 in the interior of device 10 may be mounted on one ormore substrates such as substrate 82 (e.g., printed circuits, etc.).Polarizer layer 48′ in layers 48 may overlap active display area AA andinactive display area IA to help ensure that inactive area IA has thesame appearance as active area AA.

Organic light-emitting diode display layer 88 may have a central portionthat contains pixels 22 and that forms active area AA of display 14.Organic light-emitting diode display layer 88 may also have an extendededge portion that is inactive and does not contain any pixels 22. Theinactive edge of organic light-emitting diode display layer 88 mayinclude edge portion 88′ in portion IA1 of inactive area IA and edgeportion 88″ in portion IA2 of inactive area IA. Portion 88′ of layer 88may include display driver circuitry 20 (e.g., thin-film transistors forgate driver circuitry 20B, etc.) Portion 88″ of layer 88 may includestructures that help ensure that area IA has the same appearance as areaAA (and may not contain any display driver circuitry). For example,portion 88″ may have structures of the type shown in FIGS. 5, 6, and/or7. The structures of FIGS. 5, 6, and 7 (e.g., metal and polymer layers,etc.) that are used in portion 88″ may be formed from layers of materialthat are also present in portion 88A.

FIG. 9 is a cross-sectional side view of organic light-emitting diodedisplay layer 88 in an illustrative configuration in which inactive areaIA2 has dummy pixel structures that help ensure that area IA2 has theappearance as active area portion 88A of layer 88. In portion 88A ofdisplay layer 88, layer 88 has substrate layer 30, layers 52, anode 56,emissive layer 62, cathode 42, and planarization layer 46. In extendededge portion 881″ of layer 88 (i.e., in inactive portion IA2 of inactivearea IA), dummy structures such as dummy anodes 56′, dummy emissivelayers 62′, and dummy cathode layer 42′ ensure that the appearance ofportion 881″ will match that of portion 88A (i.e., to form an opaquemasking layer for the inactive area of display 14 that matches theappearance of the active area). Dummy anodes 56′ may be patterned fromthe same layer of metal (or other material) that is used in forminganodes 56 for diodes 64 in pixels 22 of active area AA or may be formedfrom different materials. Similarly, dummy layers 62′ and 42′ may beformed from the same materials as respective layers 62 and 42 in activearea AA or may be formed from different materials. Dummy anodes 56′ maybe formed on a dielectric layer in layers 52 (e.g., an organic orinorganic dielectric layer).

Portion IA1 of inactive area IA may contain circuitry 112 for formingdisplay driver circuitry 20 and may optionally include a dummy cathodelayer such as layer 42″ (and/or dummy anodes such as dummy anodes 56′)or other structures to help ensure that the appearance of region IA2matches the appearance of active area AA. Conductive vias or othersignal paths may be used to short dummy cathode 42′ to ground 100, asillustrated by via 98, thereby preventing excess electrostatic chargefrom developing on dummy cathode 42′ when device 10 is exposed to anelectrostatic discharge event (e.g., when a user's finger contacts theedge of device 10 adjacent to dummy cathode 42′). Dummy cathode 42′ maybe formed from part of the same metal layer or other conductive layerthat forms cathode 42 and may, if desired, be electrically isolated fromcathode 42′.

If desired, the structures in extended portions 881′ and 881″ may omitsome or all of the dummy structures of FIG. 9. As shown in FIG. 10, forexample, dummy cathode layer 42′ may be formed on layer 60 withoutforming underlying dummy anodes 56′. Emissive layer material 62′ mayalso be omitted from the displays of FIGS. 9 and 10, if desired.

As shown in FIG. 11, circular polarizer 48′ need not extend to theoutermost edge of display 14. In this type of configuration, structures90 may be configured to take account of the absence of polarizer 48′above structures 90 while still ensuring that that appearance ofstructures 90 matches that of layer 88 in active area AA.

FIG. 12 is a cross-sectional side view of a portion of an illustrativedisplay for device 10 showing how structures 90 may be deposited ascoating layers on the lower surface of display cover layer 50. Polarizerlayer 48′ and display layer 88 may extend to the outer edge of display14 and may therefore be aligned with the outer edge of structures 90 orpolarizer 48′ and/or display layer 88 may extend only partway to theouter edge of display 14.

FIG. 13 is a cross-sectional side view of an edge portion of device 10in an illustrative configuration in which display cover layer 50 is heldin place by a portion of housing 12. In the example of FIG. 13, displaycover layer 50 has protruding portion 50′. Adhesive 92 may be used tosecure portion 50′ to housing 12. Elastomeric gasket structures such asillustrative gasket 200 may be interposed between display cover layer 50and housing 12 to help seal display 14 to the front face of housing 12.Other configurations for securing display 14 within housing 12 may beused, if desired.

The foregoing is merely illustrative and various modifications can bemade by those skilled in the art without departing from the scope andspirit of the described embodiments. The foregoing embodiments may beimplemented individually or in any combination.

What is claimed is:
 1. An electronic device having opposing front andrear faces, the electronic device comprising: a housing with edges; apolarizer layer that covers the front face and extends between the edgesof the housing; and an organic light-emitting diode display that iscovered by the polarizer and that has an active area with pixels thatdisplay images and an inactive area that does not display images,wherein the inactive area comprises: a first inactive area portioncomprising dummy pixel structures; and a second inactive area portionfrom which the dummy pixel structures are absent.
 2. The electronicdevice defined in claim 1, wherein the second inactive area portion isinterposed between the active area and the first inactive area portion.3. The electronic device defined in claim 1, wherein each of the pixelscomprises an anode, a cathode, and a layer of organic emissive material.4. The electronic device defined in claim 3, wherein each of the dummypixel structures comprises a dummy anode.
 5. The electronic devicedefined in claim 3, wherein each of the dummy pixel structures comprisesa dummy cathode.
 6. The electronic device defined in claim 1, whereinthe active area is rectangular and the inactive area forms a borderaround the rectangular active area, and wherein the second inactive areaportion is formed in the border.
 7. The electronic device defined inclaim 6, further comprising: a speaker port in the border formed by theinactive area.
 8. The electronic device defined in claim 7, furthercomprising: a touch sensor layer that overlaps the active area, thefirst inactive area portion, and the second inactive area portion.
 9. Anelectronic device comprising: an organic light-emitting diode displaycomprising: an active area with pixels that emit light, wherein each ofthe pixels comprises an anode, a cathode, and a layer of emissivematerial; a first inactive area portion with dummy pixel structures thatdo not emit light, wherein each of the dummy pixel structures comprisesa dummy anode; and a second inactive area portion that does not emitlight and that is free of dummy anodes; and a polarizer layer thatoverlaps the active area and the first inactive area portion.
 10. Theelectronic device defined in claim 9, wherein each of the dummy pixelstructures comprises a layer of dummy emissive material.
 11. Theelectronic device defined in claim 10, wherein each of the dummy pixelstructures comprises a dummy cathode.
 12. The electronic device definedin claim 9, wherein each of the dummy pixel structures is free of dummyemissive material and dummy cathodes.
 13. The electronic device definedin claim 9, wherein the second inactive area portion is free of dummyemissive material and dummy cathodes.
 14. The electronic device definedin claim 13, wherein the second inactive area portion is interposedbetween the first inactive area portion and the active area.
 15. Anelectronic device comprising: a polarizer layer; and an organiclight-emitting diode display that is covered by the polarizer layer,wherein the organic light-emitting diode display comprises: an activearea that displays images, the active area comprising light-emittingpixels; a first inactive area portion that does not display images, thefirst inactive area portion comprising dummy pixels that do not emitlight; and a second inactive area portion that does not display images,wherein the second inactive area portion is free of dummy pixels and isinterposed between the first inactive area portion and the active area.16. The electronic device defined in claim 15, wherein the polarizerlayer overlaps the active area and the first inactive area portion. 17.The electronic device defined in claim 16, further comprising: a touchsensor layer that overlaps the active area, the first inactive areaportion, and the second inactive area portion.
 18. The electronic devicedefined in claim 17, further comprising: a display cover layer thatoverlaps the active area, the first inactive area portion, and thesecond inactive area portion.
 19. The electronic device defined in claim15, wherein the dummy pixels are shorted to ground.
 20. The electronicdevice defined in claim 15, wherein the light-emitting pixels compriseanodes, cathodes, and light-emitting material, and wherein the dummypixels comprise dummy anodes.